Method for molding structures

Abstract

A method for molding composite structures whereby a material stack including a core having first and second opposing sides is prepared. The preparing of the material stack includes applying a fibrous support layer on at least one of the first side and the second side of the core section, applying an adhesive layer on the support layer, and applying a thermoplastic barrier layer on the adhesive layer. The method also includes preparing a resin and a mold; placing the material stack in the mold; sealing the core; infusing the mold and material stack with resin; curing the structure; and removing the structure from the mold. In one embodiment, the method creates a composite aircraft wing panel.

1. A method of manufacturing a molded composite structure, comprising:
 preparing a material stack, wherein the material stack comprises a core section having first and second opposing sides, and wherein preparing the material stack comprises: 
 applying first and second substantially fibrous support layers on the first side and the second opposing side of the core section, wherein the substantially fibrous support layers provide a vacuum path for evacuation of the core section; 
 applying an adhesive layer on the first and second support layers and on any other surface of the core not covered by the first and second support layers; and 
 applying a thermoplastic barrier layer on the adhesive layers covering all surfaces of the core; 
 preparing a resin; 
 preparing a mold; 
 placing the material stack in the mold; 
 evacuating air from the core section of the material stack through the vacuum path provided by the substantially fibrous support layers; 
 sealing the evacuated core section by curing the adhesive layer to adhere the support layers and thermoplastic barrier layer to the core section such that after sealing, the thermoplastic barrier layer prevents air from entering the core section, thereby forming an evacuated material stack; 
 infusing the mold and the evacuated material stack with the resin to form the structure; 
 curing the structure; and 
 removing the structure from the mold. 
 
   
   
     2. The method of  claim 1 , wherein material stack preparing further comprises:
 applying a laminate layer on at least one of the first side and the second side of the core section. 
 
   
   
     3. The method of  claim 1 , wherein material stack preparing further comprises:
 preparing at least two material stacks, wherein at least one of the material stacks comprises a core section having first and second opposing sides and at least one of the material stacks does not comprise a core section. 
 
   
   
     4. The method of  claim 1 , wherein material stack preparing further comprises:
 applying a laminate layer on the thermoplastic barrier layer. 
 
   
   
     5. The method of  claim 4 , wherein laminate layer applying further comprises:
 applying the laminate layer with a specified fiber orientation. 
 
   
   
     6. The method of  claim 5 , wherein mold preparing further comprises:
 reducing the modification of the fiber orientation during resin infusion. 
 
   
   
     7. The method of  claim 6 , wherein the mold comprises a shape and an internal pressure and wherein reducing further comprises:
 altering the shape and the internal pressure of the mold. 
 
   
   
     8. The method of  claim 1 , wherein mold preparing further comprises:
 preparing a first tool to form an exterior shape of the structure; and 
 preparing a second tool to form an interior shape of the structure. 
 
   
   
     9. The method of  claim 8 , wherein the second tool includes an elastomeric tool. 
   
   
     10. The method of  claim 1 , wherein placing further comprises:
 applying a release agent to the mold and to the material stack; and 
 placing the material stack in the mold. 
 
   
   
     11. The method of  claim 1 , wherein the material stack includes cavities, and wherein infusing further comprises:
 closing the mold; 
 sealing the mold; 
 creating a vacuum in the mold; and 
 infusing the mold with the resin until the cavities in the material stack are filled with resin. 
 
   
   
     12. The method of  claim 1 , wherein curing the structure further comprises:
 applying heat to the mold. 
 
   
   
     13. The method of  claim 1 , wherein curing the structure further comprises:
 applying pressure to the mold. 
 
   
   
     14. The method of  claim 1 , wherein the structure has an exterior surface resulting in a smooth laminar flow of air over that surface. 
   
   
     15. The method of  claim 1 , wherein the structure is a wing panel for an aircraft. 
   
   
     16. The method of  claim 1 , wherein the structure is a semi-span wing for an aircraft. 
   
   
     17. The method of  claim 1 , wherein the structure is a full-span wing for an aircraft. 
   
   
     18. A method of manufacturing a molded composite structure, comprising:
 preparing at least one material stack, wherein the material stack comprises a core section and cavities, wherein the core section comprises first and second opposing sides, and wherein preparing the material stack comprises: 
 applying first and second substantially fibrous support layers on the first side and the second opposing side of the core section, wherein the substantially fibrous support layers provide a vacuum path for evacuation of the core section; 
 applying an adhesive layer on the first and second support layers and on any other surface of the core not covered by the first and second support layers; and 
 applying a thermoplastic barrier layer on the adhesive layers covering all surfaces of the core; 
 preparing a resin; 
 preparing a first tool to form an exterior shape of the structure; 
 preparing a second tool to form an interior shape of the structure; 
 integrating the second tool with the material stack; 
 placing the material stack with the second tool inside of the first tool; 
 evacuating air from the core section of the material stack through the vacuum path provided by the substantially fibrous support layers; 
 sealing the evacuated core section by curing the adhesive layer to adhere the support layers and thermoplastic barrier layer to the core section such that after sealing, the thermoplastic barrier layer prevents air from entering the core section, thereby forming an evacuated material stack; 
 infusing the first tool with the resin until the cavities in the evacuated material stack are filled with resin to form the structure; 
 curing the structure; 
 removing the structure from the first tool; and 
 removing the second tool from the structure. 
 
   
   
     19. The method of  claim 18 , wherein material stack preparing further comprises:
 preparing at least two material stacks, wherein at least one of the material stacks comprises a core section having first and second opposing sides and at least one of the material stacks does not comprise a core section. 
 
   
   
     20. The method of  claim 18 , wherein material stack preparing further comprises:
 applying a laminate layer on the thermoplastic barrier layer. 
 
   
   
     21. The method of  claim 20 , wherein laminate layer applying further comprises:
 applying the laminate layer with a specified fiber orientation. 
 
   
   
     22. The method of  claim 21 , wherein first tool preparing and second tool preparing further comprises:
 reducing the modification of the fiber orientation during resin infusion. 
 
   
   
     23. The method of  claim 22 , wherein the first tool comprises a shape and an internal pressure and wherein reducing further comprises:
 altering the shape and the internal pressure of the first tool. 
 
   
   
     24. The method of  claim 18 , wherein the second tool includes an elastomeric tool. 
   
   
     25. The method of  claim 24 , wherein infusing further comprises:
 altering the internal pressure in the elastomeric tool to alter the rate of infusion. 
 
   
   
     26. The method of  claim 18 , wherein integrating further comprises:
 applying a release agent to the second tool; and placing the second tool in the material stack. 
 
   
   
     27. The method of  claim 18 , wherein placing further comprises:
 applying a release agent to the first tool; and 
 placing the material stack with the second tool inside the first tool. 
 
   
   
     28. The method of  claim 18 , wherein adhesive layer curing and structure curing occur at substantially the same temperature. 
   
   
     29. The method of  claim 18 , wherein adhesive layer curing occurs at a higher temperature than structure curing. 
   
   
     30. The method of  claim 18 , wherein adhesive layer curing occurs at a lower temperature than structure curing. 
   
   
     31. The method of  claim 18 , wherein infusing further comprises:
 sealing the first tool; and 
 creating a vacuum in the first tool. 
 
   
   
     32. The method of  claim 18 , wherein structure curing further comprises:
 applying heat to the structure; and 
 applying pressure to the structure. 
 
   
   
     33. The method of  claim 18 , wherein the structure is a wing panel for an aircraft. 
   
   
     34. The method of  claim 18 , wherein the structure is a semi-span wing for an aircraft. 
   
   
     35. The method of  claim 18 , wherein the structure is a full-span wing for an aircraft. 
   
   
     36. The method of  claim 22 , wherein the first tool has an interior surface, and the second tool has an exterior surface, and wherein reducing the modification of the fiber orientation during resin infusion comprises:
 aligning the interior surface of the first tool with the exterior surface of the second tool. 
 
   
   
     37. The method of  claim 36 , wherein the second tool comprises a semi-rigid thermoplastic bladder.